A more comprehensive list of chess related links, especially for UK sites, can be found at the UK Web Chess Guide, although it no longer appears to be kept actively maintained. This page gives just a small selection of general/local/beginner sites. If I've missed any sites out that you feel ought to be included,

• English Chess Federation, and the Junior Chess section of their website.
• UK Chess Challenge
• London Junior Chess Championships
• British Chess Magazine

• Berkshire Chess Association (some older juniors play for Berks clubs ...)
• Chiltern League (... and also for Berkshire against Bucks, Hants and Oxon)
• Southern Counties Chess Union (although Berks is apparently not affiliated - no-one seems to know why?)
• EPSCA (English Primary School Chess Association)
• ECGCF (English Counties Girls Chess Federation)
• NYCA (National Youth Chess Association)

• Barnet Knights
• Bucks Youth Chess Association (site recently revived)
• Hampshire Junior Chess
• Hertfordshire Junior Chess Academy
• Kent Junior Chess Association
• Richmond Junior Chess Club
• Surrey (Wey Valley) Junior Chess (up to Under 11)
• Surrey Youth Chess (for older age groups)
• Sussex Junior Chess
• Wiltshire Junior Chess

• Chess Kids Academy
• CHESSOPS - A Basic Guide To Chess Openings (in quaint descriptive, rather than algebraic, notation)
• Exeter Chess Club Coaching Page (some content is useful for beginners)
• 50 Chess Games for Beginners

If you would like a link to your site to be listed, just email with the details.